Boro's against-the-odds run in last season's Emirates FA Cup began with a battling win over Mansfield Town.
The Teessiders had endured a Covid-disrupted run-up to the third round tie, and fielded a much-changed XI at Field Mill including debutants Joe Gibson, William Kokolo and Caolan Boyd-Munce.
Burly striker Uche Ikpeazu gave Boro the perfect start, shrugging off two defenders before slamming an unstoppable shot into the top corner.
And when Boyd-Munce swept home a debut goal later in the first half, Chris Wilder's side seemed to have the tie all wrapped up.
But League Two Mansfield - who had won ten of their previous 11 games - clawed their way back in with goals from Oliver Hawkins and Rhys Oates.
It took a moment of inspration from Championship Player of the Month Isaiah Jones to avoid the contest going to an unwanted replay, keeping his feet well and drilling across goal towards the waiting Onel Hernandez, only for Elliott Hewitt to turn into his own net ahead of the Cuban.
The last-gasp victory earned Boro the right to take on Manchester United at Old Trafford, and after overcoming that hurdle, the Teessiders dumped out Tottenham Hotspur at the Riverside before eventually bowing out of the competition against Chelsea.
Mansfield: Bishop, O'Toole, McLaughlin (Lapslie 61'), Hawkins, Hewitt, Stirk (Law 72'), Ollie Clarke (Johnson 61'), Quinn, Maris, Bowery, Oates
Subs: Johnson, Nartey, Lapslie, Burke, Charsley, Law, Turner, Stech, Ward
Middlesbrough: Lumley, Peltier, Wood, Bamba, Kokolo (Jones 77'), Boyd-Munce (Tavernier 58'), Howson, Gibson (Crooks 58'), McNair, Ikpeazu (Dijksteel 78'), Coburn (Hernández 62')
Subs: Daniels, Crooks, Jones, Tavernier, Sykes, Dijksteel, Malley, Hernández